| Champ: |  Andrey Rublev |
| Runner: |  Paolo Lorenzi |
| Score: | 6–4, 6–2 |
| Draw: | 28 (4 / 3) |
| Seeds: | 8 |
| Type: | singles doubles |
See main article: article and 2017 Croatia Open Umag.
Fabio Fognini was the defending champion, but lost in the quarterfinals to lucky loser Andrey Rublev.
Rublev went on to win his first ATP World Tour title, defeating Paolo Lorenzi in the final, 6–4, 6–2. He was the seventh lucky loser in ATP history to win a tour-level title and the first to do so since Rajeev Ram at 2009 Newport.[1]
The top four seeds receive a bye into the second round.